/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.beam.sdk.transforms.windowing;
import java.util.Arrays;
import java.util.Collection;
import org.joda.time.Instant;
/**
* A {@link WindowFn} that places each value into exactly one window based on its timestamp and
* never merges windows.
*
* @param <T> type of elements being windowed
* @param <W> window type
*/
public abstract class PartitioningWindowFn<T, W extends BoundedWindow>
extends NonMergingWindowFn<T, W> {
/**
* Returns the single window to which elements with this timestamp belong.
*/
public abstract W assignWindow(Instant timestamp);
@Override
public final Collection<W> assignWindows(AssignContext c) {
return Arrays.asList(assignWindow(c.timestamp()));
}
@Override
public WindowMappingFn<W> getDefaultWindowMappingFn() {
return new WindowMappingFn<W>() {
@Override
public W getSideInputWindow(BoundedWindow mainWindow) {
if (mainWindow instanceof GlobalWindow) {
throw new IllegalArgumentException(
"Attempted to get side input window for GlobalWindow from non-global WindowFn");
}
return assignWindow(mainWindow.maxTimestamp());
}
};
}
@Override
public Instant getOutputTime(Instant inputTimestamp, W window) {
return inputTimestamp;
}
}